The Ship (the Triangle symbol) is moving 5A, 3F, and the Torpedo is moving 6A, 6B.  The Torpedo has a thrust of 3.

In this example, the Ship has already moved and we are on the move Torpedoes part of the turn sequence.

As the Torpedo is 3 hexes away from the Ship and it has a thrust of 3, it is often assumed that we should be able to hit the ship with it.

This would be incorrect.

Due to the Torpedo's large vector, it can not change its lateral movement enough to hit the Ship.

The green area shows where the Torpedo's End of Turn marker can be moved to by displacement.

The blue area shows all possible flight paths to one of the green hexes.

So, in spite of being only 3 hexes away from the Ship, the Torpedo can not hit it. 

Worse, even if it thrusts to move its End of Turn marker to be as close to the Ship's End of Turn marker as possible, it will still be on a divergent course.

The trick to hitting a ship with a Mode 2 Torpedo is to slow down and not fly straight at the End of Turn markers.

To do this, we need to understand where to aim our torpedoes.

We are going to do two examples with this setup.

In the first example, we will assume that our Torpedo has an insanely high thrust of 7. 

While this level of thrust is highly unusual, it is easier to show what is happening with such a high thrust as there is more room on the map.

The Ship is moving 3A, 3F and the Torpedo is moving 4A, 1F.

The Ship is 6 hexes away from the Torpedo.  However, as we saw in the first example, this doesn't mean that the Torpedo can hit the Ship.

To figure out if we can hit the ship, we need to figure out the intercept hex. 

The intercept hex is the spot on the map that the Torpedo needs to thrust towards in order to hit the Ship.  If the intercept hex is within the Torpedo's thrust rating, the Torpedo will hit the Ship.

To find the intercept hex, we simply subtract the Torpedo's vector from the Ship's position.

As the Torpedo is going 4A, 1F, the intercept hex is 4D,1C from the Ship.

The intercept hex is shown by the dark green triangle.

As the intercept hex is 7 hexes away from the Torpedo, as long as the Torpedo has a thrust of 7 or higher, it will hit the ship.

The Torpedo rotates toward the intercept hex.

The Torpedo then thrusts 7 in direction C.  This will cause the Torpedo's End of Turn marker to displace 7 hexes in direction C.

As you can see, that will cause the Torpedo's End of Turn marker to end up in the same hex as the Ship.

After adding the displacement from thrust, the Torpedo will move 4A, 1F, 7C.

After Vector Consolidation, this becomes 4B, 2C.

And thus the Torpedo will hit the Ship.

If we try this same technique with the End of Turn Marker will we still always miss the ship. 

It is because our lateral movement is a triangle.  The closer that our target is to the tip of the triangle the less lateral movement we will have to play with.

Instead we want the Target's End of Turn marker to be on the base of the triangle.

Again, we will start with this setup.  However, this time the Torpedo will have a much more reasonable thrust of 3.

From the previous example, we know that we need thrust 7 to hit the ship.  As we can not hit the ship, we need to aim for the End of Turn marker.

So, we need to calculate where our intercept hex is located. 

The first thing that we do is imagine a line from the Torpedo to the Ship's End of Turn Marker.  

Our target point will be along this line.

At this point, I need to mention that this isn't a fool-proof method.  So, don't worry too much about picking the exact hex. After all, your opponent will be maneuvering to throw-off your torpedo's pursuit.

We have modified the line slightly so that discrete hexes form the path from the Torpedo to the Ship's End of Turn marker.

Next, we count a number of hexes from the Ship's End of Turn marker equal to the Torpedo's thrust rating.

In other words, as the Torpedo has a thrust rating of 3, we want to find the hex along the line that is 3 away from the Ship's End of Turn.

We'll call this the target point

At this point, the technique is identical to that of flying towards a Ship.

We subtract the Torpedo's vector of 4A, 1F from the target point to find the intercept hex

The Torpedo rotates toward the intercept hex.

The Torpedo then thrusts 3 in direction C.  This will cause the Torpedo's End of Turn marker to displace 3 hexes in direction C.

As you can see, that will cause the Torpedo End of Turn marker to end up in the same hex as the target point.

It is important to note that very often the torpedo will not end up at the target point.  It depends on the thrust level, distance to target, etc...  However, this will get your Torpedo flying in the correct direction.

This technique will sometimes result in your torpedo thrusting to slow down.

Again, just aim at the intercept hex and your torpedo will be thrusting in the correct direction.

After adding the displacement from thrust, the Torpedo will move 4A, 1F, 3C.

After Vector Consolidation, this becomes 2A, 2B.

This will place the Torpedo is very good position to perform an intercept next turn.

We have shifted the map in the C direction.

We have updated the map to show the Torpedo's new position and End of Turn marker.

The green colored hexes show where the Torpedo can move to next turn by using displacement.

As you can see, the Ship's End of Turn marker is well within the Torpedo's kill zone 

This method isn't fool proof; however, it will get the torpedo heading in the correct direction.